The problem I'm having is certain messages aren't being forwarded to the users' Blackberries via BES. These email messages are generated by our Avaya IP telephone system, and are sent to Exchange. They have a WAV file attachment with the actual voice mail, but I'm not concerned with the attachment right now.

Checking the agent log, the Blackberry server simply doesn't see any change or new mail notification, and never sends the message. If I forward the message to another user or myself from Outlook, the forwarded message does get sent to the handheld.

I heard somewhere (not sure where) that this was the case with certain voicemail systems. They're not regular messages or something like that. Try contacting Avaya to get some input on it ... but unfortunately you may get nowhere without paying for support from either Avaya, RIM, or MSFT.

Does the avaya actually "email" the wav file across to the email sysytem or does it do some kind of 'database injection', which I think is the problem that you're getting and hdawg is referring too. I believe the problem is that the BESmgr for some reason doesn't recognise these 'new messages' to be a new email and doesn't then process that across to the 'berry

Try this by testing (if you can) by forcing the avaya to email 'externally' to the Exchange server, and see if it gets pickedup.

I'd suggest to work on Avaya & RIM / your carrier first as trying to get a sensible answer out of MSFT other than "well if you use WM6 devices then you'll be fine..."